Pulmonary Arterial Compliance Enhancement Device

ABSTRACT

Devices and methods for treating heart disease by increasing the pulmonary vascular compliance and thereby decreasing the right ventricular afterload are disclosed. Devices may include a means for reducing the cross-sectional area of the pulmonary artery during diastole and allowing the cross-sectional area to increase during systole.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/438,443, filed Jun. 11, 2019, which claims the benefit of U.S.Provisional Application Ser. No. 62/684,708, filed Jun. 13, 2018, eachof which is herein incorporated by reference in its entirety.

FIELD

The present teachings relate to methods and devices for pulmonaryhypertension and heart failure. In particular, the present teachingsrelate to methods and devices for treating pulmonary hypertension byincreasing the pulmonary arterial compliance and thereby reducing theright ventricle after-load.

BACKGROUND

Heart failure is a condition effecting millions of people worldwide.Right-sided and left-sided heart failure can both lead to pulmonaryhypertension which can in-turn lead to right heart failure. There existsa need for devices and methods for treating pulmonary arterialhypertension and right heart failure. Pulmonary arterial hypertension isdescribed by the increased pulmonary vascular resistance and decreasedpulmonary arterial compliance. While methods of treating increasedpulmonary vascular resistance may include pharmacological treatments ordiuretics, there exists a need for treating decreased pulmonary arterialcompliance. To that end, devices and methods are disclosed that increasethe volumetric pulmonary arterial compliance in order to reduce theright ventricular after-load and to treat heart failure.

SUMMARY

In general, the present teachings concerns treating right heart failureand pulmonary hypertension. To this end, devices and methods aredisclosed herein which may include implanting a compliant element to thepulmonary arterial trunk and left and right pulmonary arteries toincrease the volumetric compliance of the pulmonary arterialvasculature. Furthermore, devices and methods are disclosed herein fortreating pulmonary hypertension which may include accessing thepulmonary artery trunk, delivery an implant and adjusting the implant asneeded to increase the compliance of the pulmonary artery and reduce theafter-load on the right ventricle. Additionally, devices and methods aredisclosed which may include implanting a device inside a patient'spulmonary artery in order to increase the volumetric compliance of thepulmonary artery and providing a means for adjusting the amount ofvolumetric compliance of the artery and further providing a means forrepositioning, retrieving, or removing the implant as needed to treat apatient.

In some embodiments, an implantable compliant device is provided. Thedevice includes elongate elements that push outward on the pulmonaryartery walls thereby effectively ovalizing the hydraulic cross sectionof the pulmonary artery. The device is configured to ovalize thepulmonary artery trunk during diastole and is further configured tocompress and allow the pulmonary artery to resume a circular crosssection during systole. The inventive device may feature anchoringelements to anchor the implant to the pulmonary artery. The inventivedevice may be configured such that the outward force on the pulmonaryartery wall is adjustable during implant delivery. The inventive devicemay be configured such that the ovalization of the pulmonary arterytrunk results in a pre-determined cross-sectional area change in thepulmonary artery. The inventive device may be configured such that thecross-sectional area change and the compliance of the device are bothseparately adjustable. In some embodiments, the elongate outward pushingelements are specially configured semi-rigid or flexible wire forms. Thewire forms of the inventive device may be made from any suitablematerial and may include braided wire rope, stainless steel wire, woundwire coils, laser-cut hypodermic tubing, nitinol wire or tubing, orpolymeric tubing.

In some embodiments, a stent-like implantable compliant device isprovided. The stent like device is anchored to the pulmonary artery onthe distal end and on the proximal end and is configured to generatesignificant torque on the pulmonary artery. The torsional forcegenerated by the compliant device may be sufficient to reduce theinternal diameter of the pulmonary artery trunk, left pulmonary artery,and/or right pulmonary artery. The device may be further configured tounwind or relax in response to changes in hydraulic pressure inside thepulmonary artery. The torsional action of the device may be configuredto allow the internal diameter of the pulmonary artery to expandtemporarily during systole and then return to its reduced volume indiastole.

In some embodiments, a stent-like implantable compliant device isprovided. The stent-like implant may include a large proximal end andmay be bifurcated into two distal segments. The large proximal end maybe anchored to the pulmonary artery trunk and the two distal segmentsmay be anchored to the left and right pulmonary arteries respectively.The inventive device may be constrained during delivery with significanttorsional mechanical stress stored in the distal segments. The devicemay then be implanted into the pulmonary vasculature and then allowed toresume a more relaxed configuration, thereby imparting significanttorque to the left and right pulmonary arteries simultaneously. Thistorsion may be configured to reduce the hydraulic area of the pulmonaryarteries. The torsional stiffness of the implant may be furtherconfigured such that during systole the hydraulic area of the pulmonaryarteries is increased and in diastole the area of the pulmonary arteriesis reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary device implanted in the pulmonary arterytrunk of a heart according to some embodiments of the present teachings.

FIG. 2 illustrates an exemplary device implanted in the pulmonary arterytrunk of a heart according to some embodiments of the present teachings.

FIG. 3 illustrates an exemplary device according to some embodiments ofthe present teachings.

FIG. 4 illustrates an exemplary device according to some embodiments ofthe present teachings.

FIG. 5 illustrates an exemplary device implanted in the pulmonary arterytrunk of a heart according to some embodiments of the present teachings.

FIG. 6 illustrates an exemplary device implanted in the pulmonary arterytrunk of a heart according to some embodiments of the present teachings.

FIG. 7 illustrates an exemplary device according to some embodiments ofthe present teachings, where the exemplary device comprises a proximalanchoring element and a distal anchoring element.

FIG. 8 illustrates an exemplary delivery system according to someembodiments of the present teachings.

FIG. 9 illustrates an exemplary delivery system and an exemplary devicewhere the exemplary device is releasably connected with the exemplarydelivery system according to some embodiments of the present teachings.

DETAILED DESCRIPTION

Certain specific details are set forth in the following description andFigures to provide an understanding of various embodiments of thepresent teachings. Those of ordinary skill in the relevant art willunderstand that they can practice other embodiments of the presentteachings without one or more of the details described herein. Thus, itis not the intention of the Applicants to restrict or in any way limitthe scope of the appended claims to such details. While variousprocesses are described with reference to steps and sequences in thefollowing disclosure, the steps and sequences of steps should not betaken as required to practice all embodiments of the present teachings.Thus, it is not the intention of the present teachings to restrict or inany way limit the scope of the appended claims to such steps orsequences of steps.

Unless otherwise defined, explicitly or implicitly by usage herein, alltechnical and scientific terms used herein have the same meaning asthose which are commonly understood by one of ordinary skill in the artto which this present teachings pertain. Methods and materials similaror equivalent to those described herein may be used in the practice ortesting of the present teachings. In case of conflict between a commonmeaning and a definition presented in this document, latter definitionwill control. The materials, methods, and examples presented herein areillustrative only and not intended to be limiting.

Unless expressly stated otherwise, the term “embodiment” as used hereinrefers to an embodiment of the present teachings.

Unless a different point of reference is clear from the context in whichthey are used, the point of reference for the terms “proximal” and“distal” is to be understood as being the position of a practitioner whowould be implanting, is implanting, or had implanted a device into apatient's atrial septum from the right atrium side of a patient's heart.An example of a context when a different point of reference is impliedis when the description involves radial distances away from thelongitudinal axis or center of a device, in which case the point ofreference is the longitudinal axis or center so that “proximal” refersto locations which are nearer to the longitudinal axis or center and“distal” to locations which are more distant from the longitudinal axisor center. Another example of a context when a different point ofreference is implied is when the description involves distance towards aclinician. Under that circumstance, the term “proximal” means close tothe clinician (less into the body) and “distal” shall mean away from theclinician (further into the body). In positioning a medical device froma downstream access point, “distal” is more upstream and “proximal” ismore downstream.

As used herein, the terms “subject” and “patient” refer to an animal,such as a mammal, including livestock, pets, and preferably a human.Specific examples of “subjects” and “patients” include, but are notlimited to, individuals requiring medical assistance and, in particular,requiring treatment for symptoms of a heart failure.

As used herein, the term “lumen” means a canal, duct, generally tubularspace or cavity in the body of a subject, including veins, arteries,blood vessels, capillaries, intestines, and the like. The term “lumen”can also refer to a tubular space in a catheter, a sheath, or the likein a device.

As used herein, the term “catheter” or “sheath” encompasses any conduit,including any hollow instrument, that can be inserted into a patient'sbody to treat diseases, to administer or withdraw fluids, or to performa surgical procedure. The catheters of the present teachings can beplaced within the vascular, urological, gastrointestinal, ophthalmic,and other bodily system, and may be inserted into any suitable bodilylumen, cavity, or duct. For example, a catheter or a sheath of thepresent teachings can be used to penetrate a body tissue or interstitialcavities and/or provide a conduit for injecting a solution or gas. Theterm “catheter” or “sheath” is also intended to encompass any elongatebody capable of serving as a conduit for one or more of the ablation,expandable, or sensing elements. In the context of coaxial instruments,the term “catheter” or “sheath” can encompass either the outer catheterbody or sheath or other instruments that can be introduced through sucha sheath. The use of the term “catheter” should not be construed asmeaning only a single instrument but rather is used to encompass bothsingular and plural instruments, including coaxial, nested, and othertandem arrangements. Moreover, the terms “sheath” or “catheter” aresometime used interchangeably to describe catheters having at least onelumen through which an instrument or treatment can pass.

Unless otherwise specified, all numbers expressing quantities,measurements, and other properties or parameters used in thespecification and claims are to be understood as being modified in allinstances by the term “about.” Accordingly, unless otherwise indicated,it should be understood that the numerical parameters set forth in thefollowing specification and attached claims are approximations. At thevery least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, numerical parametersshould be read in light of the number of reported significant digits andthe application of ordinary rounding techniques.

FIG. 1 depicts a cross-sectional view of a patient's heart 101 includinga right atrium 102 and a right ventricle 103 and shows an exemplarycompliant implant device 104 implanted in the pulmonary artery trunk105. The implant device features two elongate compliant wire elements107 that are shown pushing outward on the walls of the pulmonary artery.The two wires 107 are joined at the distal joint assembly 109 by anysuitable means including crimping, welding, mechanical fit, or adhesiveusage. The distal joint assembly includes a distal threaded tube 111 anda proximal adjustment screw 113. The threaded tube includes two sideholes 115, 116 through which the wires are threaded. The proximaladjustment screw is configured to engage with threads on the inside ofthe threaded tube such that turning the screw element results in thescrew moving either distally or proximally relative to the distal jointdepending on the direction of rotation of the screw. The distal end ofthe screw may include a conical point or may include a specializedbearing surface treatment, shape, or texture. The wires may beconfigured with a relaxed configuration in which there is somepredetermined acute angle between the two wires. The proximal screwelement is configured such that it pushes outwardly on the two wireswhen it is rotated into the threaded tube thereby increasing the anglebetween the two wires. The action of the wire and proximal screw isconfigured such that this motion of the wires is reversible byunscrewing the proximal screw. In this manner, the proximal screwelement and distal joint assembly represents a means for adjusting theamount of ovalization of the pulmonary artery and thereby adjusting thepotential amount of volumetric compliance of the pulmonary artery.

The exemplary compliant wires of FIG. 1 may be made from any suitablematerial including stainless steel, nitinol, titanium, PEEK,polyurethane, platinum, platinum iridium, silver, gold, or othermetallic or polymeric materials. The complaint wires may be made fromsuper elastic or shape memory materials. The compliant wires may beformed from braided or twisted strands or as a cable. The wires may bemade from electrical discharge machined or laser cut hollow tubing. Thecompliant wires may include atraumatic tip features 117. The atraumatictip features may include widened ends, polymeric end caps, pigtailed endfeatures, or flexible articulating end segments. Polymeric end caps maybe attached to the ends of the compliant wires by heat shrinking,over-molding, gluing, press-fit, or other suitable means.

Referring now to FIG. 2, some embodiments of the present teachings aredepicted. An exemplary compliant device 104 is again depicted in apatient's pulmonary artery trunk 105. The compliant device features twocompliant elongate wires 107 joined at a distal joint assembly 109. Thejoint assembly includes a distal threaded tube 111 and a proximaladjustment screw 113. The proximal adjustment screw is configured toengage the threaded tube and to reversibly push on the elongate wires inorder to apply outward force on the pulmonary artery trunk. Thecomplaint wires are attached at the proximal joint 119. The proximaljoint may be formed by any suitable means including, for example,crimping, welding, twisting, knotting, or threading a nut over thewires.

Turning now to FIG. 3, some embodiments of the present teachings aredepicted. An exemplary compliant device 104 is depicted. The complaintdevice features two complaint wires 107 joined at the distal jointassembly 109. The joint assembly includes a distal threaded tube 111 anda proximal adjustment screw 113. The proximal adjustment screw may beconfigured in the same manner as depicted in FIGS. 1 and 2 and may beused to supply an adjustable amount of outward force on the complaintwires. The distal joint assembly is connected to a distal anchoring arm321 which is connected to a distal anchor 323. The distal anchoring armmay be connected to the distal joint assembly by any suitable means,including by crimping, swaging, gluing or use of adhesives, welding,soldering, screwing, or a mechanical fit. The distal anchoring arm mayinstead be an extension of the distal joint assembly such that theanchoring arm and joint assembly represent a single component of theinventive device. The distal anchoring arm may be made of any suitablematerial, including those materials listed above as potential materialsof manufacture for the compliant wires. The distal anchoring arm may bemade of a laser cut hypotube or may be made of super-elastic nitinol.The distal anchor may be composed of a tubular stent-like structure. Thedistal anchor is configured to expand into the distal aspect of apulmonary artery in order to anchor the implantable device to the body.The distal anchor may be specifically configured for implantation intothe left or right branch of the pulmonary artery. The distal anchor maybe connected to the anchoring arm by any suitable means, such ascrimping, swaging, threading, welding, or soldering. In someembodiments, the distal anchoring arm and the distal anchor are formedfrom a continuous section of laser cut stainless steel or nitinolhypodermic tubing. The distal anchor may be made of any suitablematerial including stainless steel, polymeric materials, PET, nitinol,cobalt-chromium alloys, gold, titanium, or other metallic alloys. Thedistal anchor may be self-expanding or may be expanded by a balloon, orotherwise mechanically expanded.

The exemplary compliant wires of FIG. 3 include a hooked wire 325. Thehooked wire is configured with a roughly 180-degree bend. The bend inthe hooked wire is configured to engage the pulmonary artery along twopoints of contact in order to bring the total contact points of thecompliant wires to three. The hooked wire is configured to furtherstabilize the implant in the pulmonary artery and to help preventmigration of the device and torsional movement of the device. Theproximal most ends of the compliant wires features atraumatic tips 117which may be simply curved inwards into the lumen of the pulmonaryartery. The atraumatic tips may be made of a substantially more flexibleor softer material than the body of the compliant wires.

Turning now to FIG. 4, some embodiments of the present teachings aredepicted. An exemplary compliant device 104 is depicted. The complaintdevice includes two compliant wires 107 connected at distal jointassembly 109. A central post 429 is also connected to the compliantwires at the distal joint assembly. The central post includes a proximalthreaded end 429 which is configured to interface with a threadeddelivery catheter. A sliding wire opening hinge element 435 slide-ablyresides on the central post and connects to the complaint wires by wayof struts 437. The distal ends of the struts are fixedly attached to thecompliant wires by attachment features 433. The central post furtherincludes flexible ratchet tines 431. The complaint wires of FIG. 4include proximal atraumatic tip features 117.

The exemplary compliant device of FIG. 4 is configured to be deliveredinto the pulmonary artery of a patient in a collapsed state. The slidinghinge element 435 is configured to slide along the central post andfeatures a coaxial connection to the central post. As the sliding hingeelement coaxially slides distally along the post it passes by theratchet tines which locks in the distal motion of the hinge element bypreventing proximal migration of the hinge element. This distal slidingof the hinge element causes the struts to angle outward and in turn pushoutward on the compliant wires. The struts are configured to hingerelative to the sliding body of the hinge element and relative to theattachment features 433. These elements of FIG. 4 therefore represent ameans of ovalizing a patient's pulmonary artery, controlling the amountof ovalization of the pulmonary artery, and thereby increasing thevolumetric compliance of the pulmonary artery.

The distal joint assembly of FIG. 4 can be created by any of the meansdisclosed above including crimping, swaging, threading, gluing,soldering, welding or other means. For example, the distal jointassembly of FIG. 4 may be formed by providing an appropriately sizedstainless steel tube which is configured to tightly contain thecompliant wires and the central post and then mechanically swaging thetube to create an interference fit. The sliding hinge element can bemanufactured by any reasonable means including laser cutting a stainlesssteel or Nitinol hypodermic tube. In some embodiments, the sliding hingeelement and struts are formed from a single laser cut stainless steeltube. The attachment features may be attached to the struts andcompliant wires by crimping, swaging, welding, gluing or othermechanical means. In some embodiments, the attachment features aresimply crimped platinum-iridium marker bands. In some embodiments, thesliding hinge element, struts, and attachment features may bemanufactured as a single polymeric component. In some embodiments, thehinge element, struts, and attachment features are configured to beinjection molded as a single component and are configured to beover-molded directly onto the compliant wires. The central post of FIG.4 can be made from any suitable material including stainless steel,PEEK, other polymeric materials, Nitinol, or other metallic materials.The ratchet tines of can be attached to the central post by any of themeans referenced above including welding, crimping, swaging, gluing, orover molding. The ratchet tines may be machined directly into thecentral post, for example, the central post may be made from a laser cutNitinol tube and the tines may then be heat-formed into a barbedposition as shown in FIG. 4.

The exemplary compliant wires of FIG. 4 may be manufactured asconventional wires or may instead be configured with a multifilamentconstruction including braided cables, bundles of 3-7 wires, woundcoils, or other constructions and configurations. The compliant wires ofFIG. 4 may be manufactured by laser cutting a metallic tube. Thecompliant wires may instead be made of a polymeric material and mayfeature a rectangular cross-section, or may instead be a tape-like,I-beam, or other cross-sectional shape.

Still referring to FIG. 4, in some embodiments, the compliant device isconfigured to be delivered through a catheter. The catheter may includean outer shaft and an inner catheter. The outer shaft may be configuredto push distally on the sliding hinge element thereby advancing thehinge element along the central post and thereby expanding the complaintwires and ovalizing the pulmonary artery. The inner catheter may beconfigured to be threaded onto the central post to substantiallymaintain the position of the compliant device relative to the pulmonaryartery. The inner catheter may be configured to transmit torque in orderto unthread the catheter from the implant once the desired amount ofovalization or force has been applied to the patient's vasculature. Insome embodiments, the inner catheter is releasable connected to thecentral post by other means including using a pull wire, lynch pin,compression fit, or rivet-like mechanism.

Turning now to FIG. 5, some embodiments of the present teachings aredepicted. FIG. 5 shows a cross-sectional view of a patient's heart 101including a right atrium 102 and a right ventricle 103 and shows anexemplary stent-like compliant implant device 501 implanted in thepulmonary artery trunk 105. The stent-like compliant implant isconfigured to have a substantially oval cross section. The stent-likeimplant is configured such that under typical systolic arterial pressurethe cross section of the implant deforms into a substantially circularcross section. The implant is further configured such that as thearterial pressure drops during diastole the implant resumes its morerelaxed state with an ovalized cross section. In this manner thestent-like complaint implant of FIG. 5 represents a means of increasingthe volumetric compliance of the pulmonary artery. In some embodiments,the stent-like implant may be configured to reside in the pulmonaryartery trunk and one or both of the main branches of the pulmonaryartery. In some embodiments, the implant may instead by made frommultiple stent-like structures. For example, in some embodiments, astent-like implant resides in the pulmonary artery trunk while a secondand third stent-like implants reside in the left and right pulmonaryartery branches. In some embodiments, the stent-like implant may beconfigured to be nested with other stent-like implants. For example, thefirst implant may be configured to apply a pre-determined amount ofovalizing stress to the pulmonary artery walls. Angiography orechocardiography may then be used to assess the amount of ovalizationand the amount of additional pulmonary arterial compliance created bythe implant. If desired, a second stent-like implant can be deployedinside the first stent-like implant to apply a second and largerpre-determined amount of ovalizing stress to the pulmonary artery walls.In some embodiments, multiple stent-like implants are designed to nestinside each other in order to adjust the amount of ovalization of thepulmonary artery and in order to fine-tune the resulting arterialpressure wave form.

The stent-like compliant implant of FIG. 5 may be made from any suitablematerial including stainless steel, Nitinol, titanium, cobalt-chromiumalloy, tantalum alloy, or polymeric materials. The stent-like compliantimplant can be configured to be delivered in a collapse configurationand then implanted in an expanded configuration. The expansion of theimplant can be self-expanding, for example, like a self-expandingNitinol stent, or may be balloon expanded or otherwise expanded by thedelivery system. The stent-like compliant implant may be made by anysuitable technology including laser-cutting, wire braiding, or stamping,rolling, and welding. In some embodiments, the stent-like compliantimplant is manufactured of Nitinol by laser cutting a strut pattern intoNitinol hypodermic tubing. The implant can then be expanded and heat setinto an ovalized shape.

Turning now to FIG. 6, some embodiments of the present teachings aredepicted. FIG. 6 depicts a cross-sectional view of a patient's heart 101including a right atrium 102 and a right ventricle 103 and shows anexemplary stent-like compliant implant device 601 implanted in thepulmonary artery trunk 105. The stent-like compliant device can bemanufactured from any of the same materials and by any of the samemethods as described above. The stent-like compliant device includesdistal anchoring elements 603 and proximal anchoring elements 605. Thedistal and proximal anchoring elements are configured to secure theimplant to the interior wall of the pulmonary artery trunk. Theanchoring elements may be small barbs or hooks which engage the surfaceof the pulmonary artery. The anchoring elements may instead fasten theimplant to the pulmonary artery by interference fit, for example,expanding the diameter of the anchoring section substantially beyond thenormal internal diameter of the pulmonary artery trunk. In someembodiments, the anchoring elements include compliant materials such asexpanded PTFE. In some embodiments, the anchoring elements includechemical fixation elements such as a material that becomes tacky when incontact with blood. In some embodiments, the anchoring elements includerotationally active elements, for example, the anchoring elements mayinclude twisted finger-like protrusions which are designed to expand theouter diameter of the anchoring section on response to the torqueapplied by the pulmonary artery wall. The compliant device furtherincludes a flow permitting waist section 607. The stent-like compliantdevice is configured to reside inside a patient's pulmonary artery trunkand either the left or right branch of the pulmonary artery. Thestent-like compliant device is further configured to supply asignificant amount of torsional force to the pulmonary artery. Thetorsional force is configured to partially collapse the internaldiameter of the pulmonary artery trunk and thereby reduce thecross-sectional area of the pulmonary artery trunk. The torsional forceis further configured such that this cross-sectional reduction is moresignificant during the low pressure diastolic phase of the heart cycleand is less significant during the high pressure systolic phase of theheart cycle. In this manner, the stent-like compliant device of FIG. 6represents a means for adjusting the pressure wave of a patient'spulmonary artery by effectively increasing the pulmonary artery wallcompliance.

In some embodiments of the present teachings, as shown in FIG. 6, thestent-like compliant device is delivered in a high-energy, wound-upstate and the anchor elements are allowed to contact the walls of thepulmonary artery trunk in this state. The implant is then allowed torelax thereby imparting a twist on the pulmonary artery due to thetorque stored in the device. In other embodiments, the stent-likecompliant implant may be deployed in a relaxed state and then latertorque may be applied to the implant through a delivery catheter. Insome embodiments, a secondary torsional element can be added to thestent-like compliant device, for example, a trifilar torsional membermay be advanced into the internal diameter of the implant and may beused to supply the torque to the implant. In some embodiments, thetorque may be slowly applied to the tissue, for example, through a meanssuch as biodegrade-able elements which prevent the implant fromimparting torque to the anatomy until after these elements degrade. Insome embodiments, the amount of torque supplied by the implant may beadjusted, for example, through a ratcheting mechanism.

Turning now to FIG. 7, some embodiments of the present teachings aredepicted. FIG. 7 depicts a stent-like bifurcated compliant device 701which includes proximal anchoring elements 605 and distal anchoringelements 603. The bifurcated compliant device includes a left arm 703intended for implantation into the patients left pulmonary artery branchand a right arm 705 intended for implantation into the patient rightpulmonary artery branch. The left and right arms of the compliant devicemay include narrowed waist sections 707. The stent-like compliant devicemay be partially or completely covered by a polymeric or biologicalmaterial, such as ePTFE, PET, or mammalian pericardium. The stent-likecompliant device may include expanded distal and proximal segments andnarrowed central segments. The narrowed central segments may beconfigured to be substantially compliant while the expanded distal andproximal segments may be configured to be substantially rigid ornon-compliant.

The compliant device including the left and right arms are configuredsuch that they can be compressed into a delivery catheter. The left andright arms are further configured such that in a delivery configurationthey are held under a significant amount of torsional stress. Thisstress can be maintained during delivery of the implant by any suitablemeans, for example, ridges on the internal diameter or external diameterof the implant may interface with the delivery system to maintain thetorsional stress on the device during delivery. The left and right armsare further configured such that after delivering the implant to thepulmonary artery branches the implant is allowed to relax towards alower stress state, thereby imparting significant torsion to thepulmonary artery branches and thereby reducing the effectivecross-sectional area of the pulmonary artery trunk. The torsion suppliedto the left and right arms and the amount of relaxation of the compliantdevice after implantation may be configured such that during the highpressure phase of the cardiac cycle the complaint device is under afirst amount of torsional stress which increases the cross sectionalblood flow area while during the low pressure phase of the cardiac cyclethe compliant device is under a second and lower amount of torsionalstress which reduces the cross sectional blood flow area.

Turning now to FIG. 8, a potential delivery system for the presentteachings is depicted. FIG. 8 depicts a cross-sectional view of apatient's heart 101 including a right atrium 102, and right ventricle103, and a pulmonary artery trunk 105. An exemplary delivery catheter803 is depicted traversing through the patient's superior vena cava 801into the right ventricle, across the patient's pulmonary valve 802 andinto the pulmonary artery. The delivery system may be configured to bedelivered over a standard interventional wire 805. The interventionalwire could be any suitable wire, for example, a 0.035″ “J” shaped wiremay be used. The delivery catheter may be made from any suitablematerial including Nylon, polyether block amide (PEBAX), polyurethane,HDPE, FEP, and PTFE. The delivery catheter may be made from a laser cutstainless steel hypodermic tube. The delivery catheter may be made froma jacketed stainless steel or otherwise metallic coil. The deliverycatheter may include braided support structure, for example braidedstainless steel wires may run through the wall of the delivery catheter.The braided stainless wires may be round, rectangular, or square incross-section and may be woven in any suitable braiding pattern. Thedelivery catheter may be pre-shaped for access to the pulmonary artery,for example, the catheter may be constructed from PEBAX heat flowed overa stainless steel braid pattern and then heat set into a shape designedto point towards the pulmonary artery. The delivery catheter may includesteerable elements, such as pull wires positioned inside the wall of thecatheter or inside the lumen of the catheter. The delivery catheter issized appropriately for insertion into the vasculature. For example, thedelivery catheter may feature a 4.3 mm outer diameter and a 3.3 mm innerdiameter and may be suitable for insertion into a standard sized accesssheath. In some embodiments, the delivery catheter is designed to enterinto the body through the jugular vein and into the superior vena cava.In some embodiments, the delivery catheter is designed to enter into thebody through the femoral vein and up through the inferior vena cava andinto the right heart. Alternative forms of access to the right heart maybe used, including radial arm access, central venous access, orminimally invasive access to the right heart and pulmonary artery.

Turning now to FIG. 9, some embodiments of the present teachings aredepicted. In FIG. 9, a cross-sectional view of a patient's heart 101including a right atrium 102, a right ventricle 103 and a pulmonaryartery trunk 105 are depicted. A delivery catheter 803 is threadedthrough a superior vena cava 801 through the pulmonary valve 802 andinto the pulmonary artery. Pre-loaded into the distal end of thedelivery catheter is an exemplary implantable compliant device similarto those disclosed above. The exemplary compliant device is configuredto be collapsed into a compressed configuration and loaded into thedelivery catheter. The exemplary compliant implant device is furtherconfigured to be releasably constrained by the delivery catheter. Theexemplary compliant device is configured to be pushed out into thepatient's pulmonary artery trunk thereby engaging the target anatomy.The exemplary compliant implant device may than be adjusted as needed toincrease the effective volumetric compliance of the pulmonary artery.The exemplary compliant device may be further configured to berecaptured and extracted if needed. The exemplary compliant device maybe configured to be repositionable if needed. Once the desired treatmenteffect has been achieved the exemplary compliant device is configured tobe released by the delivery system, and then the delivery system can beremoved from the body, leaving behind the implantable compliant device.

Although the present teachings disclose the steps of delivery,deployment, and release of a cardiac implant, one skilled the in artwould understand that these specific steps are treatment or implantspecific and thus subject to change. Thus, specific embodimentsdisclosed in the present teachings should not be construed as limiting.

Various embodiments have been illustrated and described herein by way ofexamples, and one of ordinary skill in the art will appreciate thatvariations can be made without departing from the spirit and scope ofthe present teachings. The present teachings are capable of otherembodiments or of being practiced or carried out in various other ways,for example, in combinations, all of which are within the scope of thepresent teachings and the appended claims, when applicable, explicitlyor under the doctrine of equivalents. Also, it is to be understood thatthe phraseology and terminology employed herein is for the purpose ofdescription and should not be construed as limiting.

We claim:
 1. An implantable device for increasing pulmonary artery compliance, the device comprising: a stent shaped body having a radially collapsed profile for delivery, and a radially expanded profile upon deployment, wherein the stent shaped body has a first deployed configuration where the stent shaped body has a substantially oval cross section, and a second deployed configuration where the stent shaped body deforms into a substantially circular cross section, and wherein the stent shaped body is configured to maintain its first deployed configuration during a diastolic arterial pressure, and transition into its second deployed configuration under a systolic arterial pressure.
 2. The implantable device of claim 1, wherein in its first deployed configuration, the stent shaped body applies a pre-determined amount of ovalizing stress to a pulmonary artery walls, and thereby reduce the cross-sectional area of the pulmonary artery.
 3. The implant device of claim 1 is configured to be positioned inside a pulmonary artery trunk.
 4. The implant device of claim 1 is configured to be positioned inside one of the left and right branches of a pulmonary artery.
 5. An implantable treatment system for increasing a patient's pulmonary artery compliance, the system comprising: at least two stent shaped structures, wherein each of the at least two stent shaped structures comprises a radially collapsed profile for delivery, and a radially expanded profile upon deployment, wherein each of the at least two stent shaped structures has a first deployed configuration where the stent shaped structure has a substantially oval cross section, and a second deployed configuration where the shaped structure deforms into a substantially circular cross section, wherein each of the at least two stent shaped structures is configured to maintain its first deployed configuration during a diastolic arterial pressure, and transition into its second deployed configuration under a systolic arterial pressure.
 6. The implantable treatment system of claim 5, wherein in its first deployed configuration, each of the at least two stent shaped structures applies a pre-determined amount of ovalizing stress to the pulmonary artery walls, and thereby reduce the cross-sectional area of the pulmonary artery.
 7. The implantable treatment system of claim 5 wherein one of the at least two stent shaped structures is positioned inside a pulmonary artery trunk, and the other is positioned inside one of the left and right branches of the pulmonary artery.
 8. The implantable treatment system of claim 5 comprises three stent shaped structures with one positioned inside a pulmonary artery trunk, a second one positioned inside a left branch of the pulmonary artery, and a third one positioned inside a right branch of the pulmonary artery.
 9. The implantable treatment system of claim 5 comprises two stent shaped structures with a first stent shaped structure positioned inside the pulmonary artery trunk, and a second stent shaped structure positioned inside the first.
 10. The implantable treatment system of claim 9, wherein in its first deployed configuration, the first stent shaped structure applies a first pre-determined amount of ovalizing stress to the pulmonary artery walls, and the second stent shaped structure applies a second pre-determined amount of ovalizing stress to the first stent shaped structure; and wherein the second pre-determined amount of ovalizing stress is greater than the first pre-determined amount of ovalizing stress. 